UNIVERSITY     OF     CALIFORNIA 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL    EXPERIMENT    STATION 

BERKELEY,    CALIFORNIA 


THE  DIGESTIBILITY  OF 

CERTAIN  FRUIT  BY-PRODUCTS  AS 

DETERMINED  FOR  RUMINANTS 

PART  I.     DRIED  ORANGE  PULP 
AND  RAISIN  PULP 

S.  W.  MEAD  AND  H.  R.  GUILBERT 


BULLETIN  409 

October,  1926 


UNIVERSITY  OF  CALIFORNIA  PRINTING  OFFICE 

BERKELEY,  CALIFORNIA 

1926 


Digitized  by  the  Internet  Archive 

in  2012  with  funding  from 

University  of  California,  Davis  Libraries 


http://www.archive.org/details/digestibilityofc409mead 


THE  DIGESTIBILITY  OF  CERTAIN  FRUIT  BY-PRODUCTS 
AS  DETERMINED  FOR  RUMINANTS 

PART  I.     DRIED  ORANGE  PULP  AND  RAISIN  PULP 

S.  W.  MEAD*  and  H.  K.  GUILBERTt 
INTRODUCTION 

Dairy  cattlemen  in  California  depend  to  a  large  extent  upon 
roughage  for  feed.  Comparative^  speaking,  concentrates  are  little 
used.  Barley  which  is  the  grain  most  commonly  fed,  is  usually  high 
in  price.  In  general,  all  concentrates  are  relatively  expensive.  For 
this  reason,  the  dairymen  are  interested  in  any  less  expensive  product 
which  may  be  utilized  for  feeding  purposes  and  especially  in  feeds 
which  may  supplement  the  roughage  used. 

During  the  past  few  years,  a  number  of  by-products  have  become 
available  for  replacing  some  of  the  more  expensive  feeds  which  have 
been  in  common  use  in  livestock  feeding  for  many  years.  In  many 
cases  very  little  is  known  regarding  the  nutritive  value  of  these  feeds. 
At  times,  values  not  justified  by  experimental  evidence  are  attributed 
to  certain  feeds  by  the  livestock  feeder. 

Requests  have  come  to  the  University  for  information  concerning 
the  feeding  value  of  many  new  by-products  peculiar  to  California. 
Two  of  these,  orange  pulp  and  raisin  pulp,  have  attracted  considerable 
attention.  Both  are  by-products  of  leading  fruit  industries  in  the 
state,  and  their  economic  disposal  is  of  considerable  importance.  If 
these  by-products  have  significant  feeding  values  and  can  be  purchased 
at  reasonable  prices,  the  problem  of  disposal  will  be  solved. 

Orange  pulp  is  a  by-product  in  the  manufacture  of  orange  juice, 
orange  oils,  and  other  orange  extracts.  During  the  year  ending 
December  31,  1924,  the  Exchange  Orange  Products  Company  of 
California,  produced  more  than  9000  tons  of  the  wet  or  fresh  orange 
pulp.  It  is  estimated  that  by  1930  the  volume  of  wet  pulp  to  be 
handled  will  amount  to  50,000  tons. 


*  Assistant  Professor  of  Animal  Husbandry,  Assistant  Animal  Husbandman 
in  Experiment  Station. 

t  Junior  Animal  Husbandman  in  Experiment  Station. 


4  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

In  a  practical  way  it  has  been  demonstrated  that  the  wet  pulp 
makes  a  satisfactory  feed  for  dairy  cows.  Dairymen  near  the  factory 
are  feeding  wet  pulp,  apparently  with  good  results. 

Raisin  pulp  is  being  produced  in  somewhat  smaller  quantities  than 
orange  pulp.  This  by-product  has  also  been  used  for  feeding  pur- 
poses, especially  in  the  feeding  of  beef  cattle  and  sheep,  and  in  some 
cases,  horses.  Raisin  pulp  consists  of  a  mixture  of  dry  battery  pulp, 
dry  seeder  waste,  and  stemmer  waste.  The  seeder  waste  contains 
some  fruit  adhering  to  the  stem.  The  battery  pulp  is  the  residue 
resulting  from  the  extraction  of  syrup  and  consists  of  the  raisins  after 
most  of  the  sugar  has  been  extracted.  The  pulp  is  thoroughly  dried 
and  contains  about  8  per  cent  moisture  when  leaving  the  dryer. 

Digestion  and  feeding  trials  with  these  by-products  have  been 
conducted  at  the  University  Farm  at  Davis.  The  results  of  the  diges- 
tion trials  are  reported  here,  with  a  description  of  methods  and 
equipment  used. 

METHODS    USED 

Animals. — It  has  been  definitely  shown  that  the  coefficient  of 
digestibility  for  any  given  feed  is  practically  the  same  for  all  classes 
of  ruminants.  Since  sheep  are  small  and  easily  handled  they  are 
better  adapted  to  this  type  of  investigation  than  larger  ruminants. 
For  this  reason  five  grade  wether  sheep  of  uniform  weight  and  age 
were  used. 

Digestion  stalls  and  method  of  collecting  feces. — The  animals  were 
placed  in  individual  box  stalls  4  feet  by  8  feet  equipped  with  mangers 
so  constructed  as  to  prevent  any  possible  loss  of  feed.  (See  plates 
1  and  2.)  The  feces  were  collected  by  means  of  rubber  lined  sacks 
attached  to  each  animal.     (See  plate  3.) 

Sample  containers. — One  quart  Golden  State  Mason  jars  were  used 
for  storing  the  samples  of  feeds  and  feces,  and  two  quart  jars  were 
used  for  the  roughage. 

Length  of  digestion  trial. — The  preliminary  feeding  period  was 
ten  days,  the  collection  period  fifteen  days. 

Sampling  the  feed. — The  amount  of  the  feed  necessary  to  last 
throughout  the  digestion  trial  was  spread  out  on  a  clean  floor,  and  was 
thoroughly  mixed  and  quartered.  The  individual  feeds  for  the  entire 
period  were  weighed  out  into  glazed  paper  bags ;  a  part  of  each  feed 
being  taken  from  each  of  the  four  piles.  The  bags  were  labeled, 
designating  the  animals  to  which  the  feed  contained  was  to  be  given. 


BULL.  409]         DIGESTIBILITY   OF    CERTAIN   FRUIT   BY-PRODUCTS  5 

After  every  three  or  four  portions  had  been  weighed,  a  small  amount 
of  the  feed  was  taken  from  each  of  the  four  piles  to  form  a  composite 
sample  for  chemical  analysis.  The  hay  was  finely  cut,  then  mixed 
and  sampled  as  above. 


Feeding  manger  with  front  lowered  to  show  construction  of  manger  and 
stanchion  used  for  fastening  animal  while  eating.  Animals  were  kept  in 
stanchions  until  all  feed  had  been  consumed. 


Amount  fed. — The  amounts  of  the  various  feeds  used  were  cal- 
culated to  satisfy  the  maintenance  requirements  of  the  animal.  All 
of  the  feed  offered  was  eaten  except  a  small  amount  of  alfalfa  stems 
which  were  not  cut  finely  enough  in  the  original  cutting.     The  stems 


b  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

refused  were  ground  in  a  feed  grinder  and  replaced  in  the  manger  of 
the  animal  which  had  originally  refused  them.  In  every  case  this 
reground  feed  was  consumed  by  the  animal.  In  this  way,  there  was 
no  refused  feed  to  consider  in  the  final  calculations. 


Feeding  manger  with  front  lowered  to  show  animal  with  head  fastened 
to   prevent  loss   of  feed. 

Handling  the  feces. — The  collection  bags  were  emptied  twice  daily. 
The  feces  were  immediately  weighed  and  aliquot  portions  of  the  feces 
of  each  animal  placed  in  containers  which  had  previously  been  rinsed 
in  a  10  per  cent  alcoholic  solution  of  thymol.    In  addition,  powdered 


Bull.  409]       DIGESTIBILITY  of  certain  fruit  by-products  7 

thymol  was  sprinkled  over  the  feces  after  they  were  transferred  from 
the  scales  to  the  jars,  to  the  amount  of  5  grams  of  thymol  to  each  jar. 
The  jars  were  immediately  placed  in  a  refrigerator  where  they 
remained  until  the  next  time  the  feces  were  collected.  The  refrigerator 
was  maintained  at  a  temperature  varying  from  28  to  35  degrees 
Fahrenheit. 


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fBp' 

jm 

Illustrating  method  used  for  collecting  feces. 

At  the  end  of  the  collection  period  the  contents  of  the  several 
jars  representing  the  total  feces  collected  from  each  animal  were 
thoroughly  mixed,  ground,  remixed  and  sampled  for  chemical 
analysis. 


RESULTS   OF   THE   ORANGE    PULP   AND    RAISIN    PULP 
DIGESTION   TRIALS 

The  orange  pulp  and  raisin  pulp  were  fed  with  alfalfa  hay,  and 
since  the  digestibility  of  the  available  hay  was  not  known,  a  digestion 
determination  was  made,  using  the  same  methods  and  equipment  as 
those  used  in  the  case  of  the  orange  pulp  and  raisin  pulp.  A  sufficient 
amount  of  this  hay  was  set  aside  for  the  three  trials. 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


APPARENT    DIGESTIBILITY   OF    DRIED    ORANGE    PULP 

The  orange  pulp  used  in  this  trial  was  dried  to  approximately  15 

per  cent  moisture  and  finely  ground  in  order  to  facilitate  handling. 

The  composition  of  the  feeds  and  feces,  total  amounts  of  the  feeds 

consumed  by  the  animals,  feces  collected,  and  results  of  the  orange 

pulp  trial  are  shown  in  the  following  tables: 


TABLE   1 

Total  Feed  Consumed  and  Total  Feces  Collected 


Animal  number 

Alfalfa  hay 

Orange  pulp 

Feces 

1 

Grams 

7800 

7800 

7800 

11550 

8775 

Grams 

3975 
3975 
3975 
5850 
4425 

Grams 

7869  1 

2 

7948  4 

3 

7832.9 

4 

11965  5 

5 

10049  0 

TABLE  2 

Chemical  Analyses  of  Feces  and  Feeds 


Feces: 

Animal  Number 

Dry 

matter 

Crude 
protein 

Nitrogen-free 
extract 

Ether 
extract 

Crude 
fiber 

1 

Per  cent 

37.43 
37.44 
37.60 
36.40 
33.93 

90.78 
87.50 

Per  cent 

4.39 
4.29 
4.28n 
4.17 
3,82 

15.30 
7.70 

Per  cen  t 

11.21 
11.56 
11.55 
11.15 
10.34 

37.86 
66.96 

Per  cent 

1.85 
1.92 
1.83 
1.79 
1.64 

1.81 
1.68 

Per  cent 

14.92 

2 

14.70 

3 

14.90 

4 

14.36 

5 

13.51 

Feeds: 

Alfalfa  hay 

28.00 

Dried  orange  pulp 

7.81 

TABLE  3 

Coefficients  of  Digestibility  of  Alfalfa  Hay  Used  in  Digestion  Trials  with 
Orange  Pulp  and  Eaisin  Pulp 


Dry  matter 

Crude  protein 

Nitrogen-free 
extract 

Ether  extract 

Crude  fiber 

Per  cent 

63.31±.13 

Per  cent 

77.00±.10 

Per  cent 

73.45±.27 

Per  cent 

20. 31  ±.26 

Per  cent 

48.49±.20 

Bull.  409]       digestibility  of  certain  fruit  by-products 


TABLE  4 
Coefficients  of  Digestibility  of  Dried  Orange  Pulp 


Animal 
Number 

Dry 

matter 

Crude 
protein 

Nitrogen-free 
extract 

Ether 

extract 

Crude 
fiber 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

1 

90.0146 

76.8222 

96.3110 

50.4819 

84.2074 

2 

89.1385 

78. 2817 

94.9318 

39.9535 

86.0289 

3 

90.0214 

80. 1565 

95.4629 

53.8307 

86. 4517 

4 

90.0702 

79.4711 

95.5753 

51.5863 

88. 5489 

5 

87. 4283 

77.9747 

94. 6967 

48.5739 

73.3941 

Average 

89. 33 =h. 31 

78.54zt.35 

95.40d=.17 

48.89±1.44 

83.73=hl.61 

APPARENT   DIGESTIBILITY   OF    RAISIN    PULP 

The  composition  of  the  feeds  and  feces,  total  amounts  of  feeds  con- 
sumed by  the  animals,  feces  collected,  and  results  of  the  raisin  pulp 
trial  are  shown  in  the  following  tables : 


TABLE  5 
Total  Feed  Consumed  and  Feces  Collected 


Animal  Number 

Alfalfa  hay 

Raisin  pulp 

Feces 

1 

Grams 

7800 

7800 

7800 

11550 

8775 

Grams 

3975 
3975 
3975 
5850 
4425 

Grams 

9137.8 

2 

8699.4 

3 

8857.3 

4 

14111.5 

5 

10163.0 

TABLE  6 
Chemical  Analyses  of  Feces  and  Feeds 


Feces: 

Animal  Number 

Dry 
matter 

Crude 
protein 

Nitrogen-free 
extract 

Ether 
extract 

Crude 
fiber 

1 

Per  cent 

49.03 
52.39 
50.25 

48.85 
50.01 

90.58 
88.68 

Per  cent 

6.23 
6.46 
6.33 
6.01 
6.22 

15.46 
9.58 

Per  cent 

17.90 
19.22 

17.87 
18.32 
18.12 

37.72 
45.57 

Per  cent 

1.68 
1.82 
1.67 
1.60 
1.69 

1.80 
10.54 

Per  cent 

19.37 

2 

19.99 

3 

19.53 

4 

18.20 

5 

19.15 

Feeds: 

Alfalfa  hay 

27.80 

Raisin  pulp 

19.32 

10 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


TABLE   7 
Coefficients  of  Digestibility  of  Eaisin  Pulp 


Animal 
Number 

Dry 

matter 

Crude 
protein 

Nitrogen-free 
extract 

Ether 
extract 

Crude 
fiber 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

1 

46.4436 

23.3463 

52.8195 

90.0656 

14.9727 

2 

44.2490 

25.2633 

50.8128 

88.9151 

19.0068 

3 

47.2796 

25.6074 

57.7383 

91.3998 

20.2021 

4 

41.1164 

21.9598 

46.4074 

90. 2531 

19. 1076 

5 

44.8001 

24.4921 

52.2496 

90. 1638 

19.4333 

Average 

44.78±.64 

24.13±.40 

52.01±1.10 

90.16=b.24 

18.54±.55 

TABLE  8 

Digestibile  Nutrients  Contained  in  Various  Common  Feeds  Compared  with 

Dried  Orange  Pulp  and  Eaisin  Pulp 


Feeding  stuff 


fBarley 

Dried  orange  pulp 

fDried  beet  pulp 

fAlfalfa  hay,  all  analyses 
Raisin  pulp 


Total  dry 
matter  in 
100  pounds 


Pounds 

90.7 
87.5 
91.8 
91.4 

88.7 


Digestible  nutrients  in  100  pounds 


Crude 
protein 


Pounds 

9.0 
6.0 
4.6 
10.6 
2.3 


Carbo- 
hydrates 


Pounds 

66.8 
70.4 
65.2 
39.0 
27.3 


Fat 


Pounds 

1.6 
0.8 
0.8 
0.9 
9.5 


"Total 


Pounds 

79.40 
78.31 
71.60 
51.60 
50.98 


*  Total  includes  fat  times  the  factor  2.25. 

t  Henry  and  Morrison,  Feeds  and  Feeding,  Table  3,  Appendix  1923  Ed. 


DISCUSSION  OF   RESULTS 

The  nutritive  value  of  any  feed  is  dependent  largely  upon  the 
digestibility  of  its  various  constituents.  This  digestibility  is  calcu- 
lated by  subtracting  the  amount  of  a  given  nutrient  in  the  feces  from 
the  amount  of  the  same  nutrient  in  the  feed  consumed  by  the  animal. 
This  difference,  expressed  in  terms  of  percentage  of  the  total  amount 
ingested,  is  called  the  coefficient  of  digestibility.  This  method  gives 
only  the  apparent  digestibility.  However,  since  it  is  the  one  that  has 
been  used  in  all  previous  digestion  trials,  a  fair  comparison  between 
the  digestibility  of  the  feeds  reported  here  and  those  reported  by  other 
investigators  is  made  possible. 

According  to  the  figures  presented  in  Table  8,  orange  pulp  com- 
pares very  favorably  with  barley  in  total  digestible  nutrients,  though 


Bull.  409]        DIGESTIBILITY  of  certain  fruit  by-products  11 

somewhat  lower  in  amount  of  digestible  crude  protein.  Dried  beet 
pulp,  which  is  used  in  very  large  quantities  by  dairymen  throughout 
the  country,  contains  on  the  average  4.6  per  cent  digestible  crude 
protein,  whereas,  the  orange  pulp  used  in  this  trial  contained  6.0 
per  cent.  Orange  pulp  contains  78  per  cent  total  digestible  nutrients, 
while  dried  beet  pulp  contains  71.6  per  cent  total  digestible  nutrients. 
In  a  practical  way,  however,  a  difference  in  feeding  value  as  small 
as  these  figures  indicate  is  of  no  great  economic  importance. 

The  value  of  the  raisin  pulp  as  shown  by  these  trials  was  much 
below  that  of  either  barley,  dried  beet  pulp,  or  dried  orange  pulp. 
The  raisin  pulp  contained  a  larger  amount  of  crude  protein  than 
dried  orange  pulp,  but  the  coefficient  of  digestibility  of  the  protein 
in  orange  pulp  was  78.5  while  that  of  the  raisin  pulp  was  only  24.1. 
As  shown  in  tables  4  and  7,  89  per  cent  of  the  total  dry  matter  in 
orange  pulp  was  digested,  but  only  44  per  cent  in  the  raisin  pulp. 

According  to  the  results  of  the  digestion  trials  herewith  reported, 
dried  orange  pulp  should  have  a  feeding  value  approximating  that  of 
barley,  dried  beet  pulp,  and  other  feeds  of  a  similar  nature.  Raisin 
pulp  should  have  a  feeding  value  of  approximately  two-thirds  the 
value  of  these  feeds. 

The  comparative  values  of  these  feeds  for  beef  and  milk  production 
will  be  reported  later. 

ACKNOWLEDGMENT 

The  writers  wish  to  express  their  appreciation  for  the  assistance 
given  them  by  Mr.  H.  W.  Allinger,  of  the  Division  of  Chemistry,  in 
carrying  out  the  analytical  work. 


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